The present invention relates to endotracheal tube or catheter guides, and in particular to adjustable stops for use with such guides to set the depth of penetration of the guide into the endotracheal tube or catheter.
A variety of guides and stylets are available for use with flexible endotracheal tubes and catheters to aid the physician in intubating such instruments with a minimum of trauma to the patient. The guide or stylet is usually inserted within the endotracheal tube or catheter before intubation into the patient. After intubation, the guide or stylet is carefully withdrawn.
Of considerable importance to the physician is the ease by which the guide can be configured along with the endotracheal tube or catheter into a semi-permanent shape best suited for intubation; the necessity for adjustably setting and permanently maintaining the depth of penetration of the distal end of the guide within the tube or catheter; and the ease with which the guide can be withdrawn from the tube or catheter after intubation.
One type of stylet or guide in wide use consists of a long thin wire of maleable metal, such as soft iron, copper, or aluminum, which has been completely encapsulated and hermetically sealed with a tough layer of elastomeric polymer, such as nylon, polyolefin, polypropylene, or the like. While such guides have been relatively easy to configure into a desired shape and can be withdrawn from an intubated endotracheal tube or catheter without difficulty, some problems have been encountered in setting and maintaining a predetermined depth of penetration of the guide into the tube or catheter.
One method employed to preset the depth of penetration has been to form a right-angle or ninety-degree bend near the proximal end of the guide for abutment against one side of the opening to the endotracheal tube or catheter. Another method has been to form a small closed or circular loop with the proximal end of the guide with a portion of the loop abutting the open end of the endotracheal tube or catheter. Neither of these methods has been found to be completely satisfactory, nor do they offer any satisfactory way by which the physician can grasp the proximal end portion of the guide or stylet for manipulation without the risk of accidentally rebending or altering the shape of the proximal end, thereby causing the distal end to dangerously penetrate beyond minimum safe limits.
To alleviate this serious problem, an improved endotracheal tube stylet has been introduced employing an adjustable stop of tough synthetic rubber mounted upon and slidable along the length of the stylet for setting the desired depth of penetration. A description of this new stylet appears in the March-April 1974 issue of Journal of the International Anesthesia Research Society, Vol. 53, No. 2, pages 341-342.
A further solution to the above-mentioned problems appears in U.S. Pat. No. 3,957,055, wherein an adjustable stop has been described which performs not only the function of setting and maintaining the desired preset depth of penetration but also serves the additional function of providing an anchor for the proximal end of the guide, thereby enabling the proximal end portion of the guide to be formed into a convenient and useful handle. The present invention is concerned with further improvements in adjustable stops for use with endotracheal tube or catheter guides to overcome the above-mentioned problems.